On Thu, Apr 16, 2020 at 10:09:30AM -0700, Jianxin Xiong wrote: > This patch set adds dma-buf importer role to the RDMA driver and thus > provides a non-proprietary approach for supporting RDMA to/from buffers > allocated from device local memory (e.g. GPU VRAM). How exactly does this allow access to GPU VRAM? dma_buf_attach() cannot return non-struct page memory in the sgt, and I'm not sure the API has enough information to do use the p2pdma stuff to even establish a p2p mapping. We've already been over this in another thread.. There is a way to improve things to get there, but I don't understand how this patch series is claming to be able to work with VRAM - if it is that means there is a bug in a GPU driver that should be squashed. Other than that, this seems broadly reasonable to me as a way to access a DMA buf pointing at system memory, though it would be nice to have a rational for why we should do this rather than rely on mmap'd versions of a dma buf. Jason
